Antifriction bearing with a clip-on sensor

ABSTRACT

An antifriction bearing assembly has rolling elements and a magnetic encoder ring housed in an outer ring with two portions which can have different diameters. A sensor is removably attached to the outer ring in alignment with the encoder ring. Various seal assembly configurations may be used to seal the bearing while accommodating the sensor.

This is a division of application Ser. No. 787,865 filed Nov. 5, 1991,which is a division of Ser. No. 680,437, Apr. 4, 1991, U.S. Pat. No.5,103,170, which is a division of application Ser. No. 515,031 filed May21, 1990, U.S. Pat. No. 5,081,416. which is a division of applicationSer. No. 315,624 as originally filed on Feb. 24, 1989, now U.S. Pat. No.4,940,936

This invention relates to antifriction bearings used in conjunction witha speed sensor assembly; more particularly, it relates to bearings usedwith an encoder ring attached to a rotating shaft and a sensor which isremovably attached to a stationary member in alignment with the encoderring so as to allow the sensor to detect the passage of alternatingmagnetic poles. This invention is particularly well-suited for use in awheel spindle bearing, e.g., in a rear wheel bearing of a rear-wheeldrive vehicle.

Prior art patents disclose structures which combine spindle bearingswith sensor assemblies in various configurations so as to provide anelectrical output signal whose frequency is proportional to therotational speed of the associated axle or shaft. An example of thistype of prior art is disclosed in U.S. Pat. No. 4,732,494 for a "BearingOr Roller Bearing With Data Sensor" issued in the names of Roger Guersand Georges Godard on Mar. 22, 1988. Other prior art patents disclosevarious means for attaching a magnetic encoder ring to a rotating shaftwhen the encoder ring is not attached directly to a bearing component.An example of this type of prior art is disclosed in European PatentApplication No. 86305758.4 for a "Magnetic Ring For Detecting TheRotation Of An Object" filed in the names of inventors Kenji Hattori andShinichi Tanaka, and in the names of applicants Honda Giken KogyoKabushiki Kaisha, and Dainippon Ink and Chemicals, Inc. on Jul. 25,1986, and published on Nov. 3, 1987.

One of the main problems with the prior art is that the sensor isnormally installed in the bearing assembly, or in close proximity to abearing, so that the sensor becomes a relatively permanent part of theassembly. Repair and maintenance problems require extensive disassemblyof adjacent components in order to gain access to the sensor. Normally,the entire bearing assembly must be replaced in order to correct aproblem with the sensor. Another problem with the prior art is that ofmagnetic encoder ring retention on a rotating shaft. Often, the magneticencoding means is provided by the magnetic flux concentration action ofthe teeth of a gear wheel, or tone wheel, which is assembled onto arotatable shaft. This method is used with variable reluctance sensorsystems which do not adequately address the problem of retaining anencoder ring on a rotating shaft, where the magnetic encoder ring ismade of a synthetic resin material having magnetic material embedded inthe ring.

The bearing assembly of the present invention overcomes these problemswith a removable sensor and an encoder retainer ring. The sensor can beserviced or individually replaced in a relatively easy manner. Theencoder retainer ring provides proper mechanical support for a syntheticresin encoder ring.

Briefly described, the bearing assembly of the present inventioncomprises a bearing with an outer ring having two portions withdifferent diameters. The outer ring also houses a magnetic encoder ring,attached to a rotatable shaft by an encoder retainer ring, andaccommodates a clip-on assembly for the sensor. In addition, a uniqueseal assembly accommodates a sensor mount utilized in the clip-on sensorassembly. A modified embodiment of the bearing assembly utilizes amodified seal assembly installed inside one end of the outer ring.

This invention may be better understood by reference to the followingdetailed description and drawings in which:

FIG. 1 is a side sectional view of a typical prior art bearing assemblypresently in use;

FIG. 2 is a side sectional view of the preferred embodiment of thebearing assembly of the present invention;

FIG. 3 is an exploded view of the bearing assembly shown in FIG. 2;

FIG. 4 is an end view of the clip-on sensor arrangement shown in FIGS. 2and 3, taken along line 4--4 in FIG. 2;

FIG. 5 is an enlarged side sectional view of the same bearing assemblytaken along line 5--5 of FIG. 4;

FIG. 6 is a perspective view of the sensor and sensor mount shown inFIGS. 4 and 5, showing the bottom of the mount;

FIG. 7 is a perspective view of the preferred embodiment of the encoderretainer ring;

FIG. 8 is another perspective view of the same encoder retainer ringwith a magnetic encoder ring shown mounted on the retainer ring;

FIG. 9 is a perspective view of a modified embodiment of the encoderretainer ring;

FIG. 10 is another perspective view of the same modified embodimentshown in FIG. 9, depicting the encoder retainer ring with a magneticencoder ring attached to it;

FIG. 11 is a partial perspective view of the preferred embodiment of thebearing assembly seal, including a sectional view of the seal;

FIG. 12 is another perspective view, similar to FIG. 11, of a modifiedembodiment of the seal assembly;

FIG. 13 shows a second modified embodiment of the bearing assembly sealin a view similar to FIGS. 11 and 12;

FIG. 14 is another modified seal assembly arrangement illustrated in aside sectional view;

FIG. 15 is an end view of a modified embodiment of the clip-onarrangement for the bearing assembly sensor, comparable to the viewshown in FIG. 4;

FIG. 16 is an end view of a second modified embodiment of the sensorclip-on arrangement;

FIG. 17 is an end view of a third modified embodiment of the sensorclip-on arrangement;

FIG. 18 is an end view of a fourth modification of the sensor clip-onarrangement;

FIG. 19 is an end view of a fifth modification of the sensor clip-onarrangement, utilizing the modified seal assembly shown in FIG. 13; and

FIG. 20 is a side sectional view of a modified embodiment of the bearingassembly, comparable to the view shown in FIG. 2.

In the various figures, like parts are referred to by like numbers.

Referring to the drawings, and more particularly to FIG. 1, a prior artbearing assembly 10 presently in use is illustrated. The bearingassembly comprises a radial bearing 20 mounted on a shaft 30, a magnetictone wheel 40, a sensor 50 which detects or senses magnetic fieldperturbations caused by the teeth of tone wheel 40 passing sensor 50, aseal assembly 60, and a wheel and hub assembly 70. The electrical outputsignal from sensor 50 is transmitted via lead 80, and sensor 50 is heldin alignment with tone wheel 40 by a support bracket 90.

Turning now to FIGS. 2 and 3, the preferred embodiment of the bearingassembly 100 of the present invention comprises a radial bearing 110mounted in an axle tube 102 around a shaft 120, a magnetic encoder ring130 mounted on an encoder retainer ring 140, a sensor assembly 150 fordetecting the magnetic encoded signal from encoder ring 130, a sealassembly 160, a wheel and hub assembly 170, and an output lead 180 fortransmitting the output signal from sensor assembly 150. The sensorassembly 150 is replaceably attached to an outer ring 112 by a clip-onassembly 190. The wheel and hub assembly 170 is located on the outerside of bearing assembly 100, and the opposite side of assembly 100 isthe inner side.

The radial bearing 110 has a full complement of rolling elements 114housed in outer ring 112. It should be noted that rolling elements 114could be retained by a cage or a retainer in alternative bearingconfigurations. Outer ring 112 has two portions -- a larger diameterportion 116 and a smaller diameter portion 118. The smaller diameterportion 118 has a lipped washer 144 installed in its outer axial end,adjacent to seal assembly 160, to provide a thrust surface to receivethrust loads during installation of the axle or shaft 120 into outerring 112 and to receive the relatively small thrust load generated bythe limited axial movement of the magnetic encoder ring 130 and toprovide axial retention of rings 130, and 140 when seal assembly 160 isremoved from ring 112 for some reason, such as maintenance orreplacement. A shoulder 122 joins portions 116 and 118, and provides asurface for receiving thrust load from rolling elements 114; the encoderand retainer rings in portion 118 are thereby isolated from the thrustload.

Turning now to FIGS. 2-6, sensor assembly 150 comprises a sensor mount152 and a sensor 154. The sensor protrudes from the bottom of mount 152(see FIG. 6) so as to mate with an opening 156 in the smaller diameterportion 118 of outer ring 112. An O-ring seal 158 is installed aroundthe sensor 154 and sits on top of outer ring portion 118 around opening156. It can be seen from FIGS. 3, 4, and 6 that the bottom surface ofmount 152 is curved in order to mate with the outer surface of outerring portion 118. Sensor 154 is a Hall-effect sensor in the preferredembodiment; however, the sensor should not be limited to a Hall sensor.

Clip-on assembly 190 comprises two clips 192, two pins 194 for attachingclips 192 to sensor mount 152, and a fastener 196 to connect clips 192together at their ends opposite sensor mount 152. Sensor mount 152 alsohas four bore holes 198, into which pins 194 are inserted. Each pin 194is supported by a pair of holes 198 in mount 152 so as to leave thecentral portion of the pin exposed in order to allow a clip 192 to latchonto the pin. Sensor mount 152 also has an aperture 188 through itsinner side surface to accommodate output lead 180. It should be notedthat aperture 188 could be located anywhere on mount 152 as long as theoutput lead 180 can be adequately accommodated and routed to its desireddestination.

Turning now to FIGS. 7 and 8, the preferred embodiment of the encoderretainer ring 140 is depicted. Ring 140 has two end rims 142 which areconnected by a plurality of crossbars 146. The crossbars are bentslightly inwardly (see FIG. 5) in order to provide means for pressfitting the ring 140 to a rotating shaft, or axle 120. Theconfigurations of the end rims 142 and the crossbars 146 can be modifiedin numerous ways in order to provide the desired amount of force in theinterference fit between the retainer ring 140 and the shaft 120. Atleast one of the crossbars 146 is partially cut, and the partialcrossbar(s) bent radially outwardly as shown by partial crossbar 148 inFIG. 7. Partial crossbar 148 is then mated with a groove 132 in themagnetic encoder ring 130, thereby fastening ring 130 to retainer ring140. Ring 140 is tightly attached to shaft 120, and encoder ring 130 isattached to retainer ring 140, so that magnetic encoder ring 130 rotateswith shaft 120.

Turning now to FIGS. 9 and 10, modified means for retaining a magneticencoder ring 230 to shaft 120 is illustrated. A modified encoderretainer ring 240 comprises an annular flange 242, which extendsaxially, and a radial portion which projects inwardly from one axial endof flange 242 and comprises a plurality of castellated teeth 244 andgrooves 246 between the teeth 244. These teeth make an interference fitwith shaft 120 so that ring 240 is snugly attached to the shaft.

Ring 240 is split at 248 so that it can be spread open circumferentiallyto facilitate installation of the ring onto a shaft or axle. Magneticencoder ring 230 is attached to retainer ring 240 by means of multiplefingers 232 which extend axially through matching grooves 246 (see FIG.10). Fingers 232 ensure radial coupling between rings 230 and 240

so that magnetic encoder ring 230 rotates with shaft 120. The fingersmay also be configured to limit axial movement of the encoder ring 230by snapping into retainer ring 240, if desired, although axial movementwould normally be limited by outer ring 112. Axial movement of magneticencoder ring 230 could also be limited by installing a retainer ring 240at each end of the encoder ring; in this case, encoder ring 230 wouldhave fingers 232 projecting axially from both axial ends to match thegrooves 246 in each of the two retainer rings 240.

FIG. 11 shows the preferred embodiment of the seal assembly 160 of thepresent invention. The seal assembly comprises a seal member 161 and ametallic member 165. Seal member 161 comprises an outer annular portion162, a radial portion 163, and an inner annular portion 164. Seal member161 is made of a rubber or rubber-like material; it could also be madeof any suitable elastomeric material. A garter spring 169 pressesannular portion 164 to shaft 120 to ensure a snug seal. Metallic member165 also has an outer annular portion 166 and a radial portion 167.Portions 166 and 167 make a snug fit with outer annular portion 162 andradial portion 163, respectively, of seal member 161. Metallic member165 provides additional sealing protection from the environment, e.g.,moisture, contaminants, etc., for seal member 161 and the componentsinside outer ring 112.

Outer annular portions 162 and 166 make a snug press fit around theouter surface of the outer end of outer ring 112 (see FIGS. 2, 3, and5). A rectangular aperture 168 penetrates the inner axial edge ofportions 162 and 166 in order to accommodate the sensor mount 152described above.

Two modified embodiments of the seal assembly are illustrated in FIGS.12 and 13. Seal assembly 260 in FIG. 12 has a modified aperture 268having four enclosed sides through portions 162 and 166, rather thanonly three sides. Otherwise, assemblies 160 and 260 are alike. Sealassembly 360 shown in FIG. 13 has an aperture 368 similar to aperture168 in FIG. 11, except that adjacent to aperture 368 are two curled-backhook members 370 for connecting sensor mount 152 to the seal assembly360. FIG. 19 shows a clip-on assembly 690 which could mate with sealassembly 360 by connecting to hook members 370.

FIG. 14 depicts an alternate embodiment 460 of the seal assembly whichutilizes an outer ring 412, similar to outer ring 112 in FIG. 2, whichhas two portions -- a larger diameter portion 416 and a smaller diameterportion 418. The seal assembly 460 is housed inside smaller diameterportion 418 so as to seal the annular space between shaft 120 and ring412. Assembly 460 comprises a seal member 461 and a metallic member 465.Seal member 461 comprises an outer annular portion 462, a radial portion463, and an inner annular portion 464. Metallic member 465 comprises anouter annular portion 466 and a radial portion 467. A garter spring 469presses portion 464 against the shaft 120. It should be noted thatportion 418 can be extended axially in order to accommodate rollingelements or an encoder ring, as desired.

Turning now to FIGS. 15-19, modified embodiments of the clip-on sensorarrangement 190 shown in FIGS. 2-6 are illustrated in end views whichreveal how the sensor assemblies are clipped onto the outer ring 112.FIG. 15 depicts a one-piece clip 292 which fits over the sensor assembly150 and the outer ring 112 without the aid of any additional fasteners,such as bolts or screws. FIG. 16 shows a one-piece clip 392 which fitsaround the sensor assembly and outer ring; the two ends of clip 392 areconnected by interlocking the two hooks 394 at each end.

FIG. 17 illustrates a two-piece clip 492 which clips onto flanges 494 onthe top sides of sensor mount 452. FIG. 18 depicts a one-piece clip 592whose two ends attach to sensor mount 552 by means of a pin 594 on oneside of mount 552 and by clipping onto a flange 596 on the other side ofmount 552. Finally, the modified clip-on assembly 690 of FIG. 19utilizes a modified clip 692 which is adapted to accommodate themodified seal assembly 360 of FIG. 13. The two hooked ends 694 of clip692 mate with the two curled back hook members 370 of seal assembly 360.

Turning finally to FIG. 20, a modified bearing assembly 200 comprises aradial bearing 710 mounted on a shaft 720 and housed in a smallerdiameter portion 718 of an outer ring 712, a magnetic encoder ring 730,an encoder retainer ring 740, a sensor assembly 750, a seal assembly760, an output lead 780 from sensor 754, and a clip-on assembly (notshown) similar to the assembly shown in FIGS. 2 and 3. It should benoted that the rolling elements 714 are housed in the smaller diameterportion 718 rather than the larger diameter portion 716; conversely, theencoder retainer ring 740 and the magnetic encoder ring 730 are housedin the larger diameter portion 716 instead of portion 718. It shouldalso be noted that seal assembly 760 is similar to the modified sealassembly embodiment shown in FIG. 14, with the seal member 761 situatedinside larger diameter portion 716 of outer ring 712 instead of fittingon the outside of the outer ring in a manner similar to that shown inthe preferred embodiment (see FIGS. 2, 3, 5, and 11). The modifiedbearing assembly 200 is suitable for lighter load applications than thepreferred embodiment assembly 100 of FIGS. 2 and 3.

We claim:
 1. An antifriction bearing assembly for use with a rotatable shaft, said bearing assembly comprising:a bearing having multiple rolling elements housed in an outer ring having two portions, a larger diameter portion and a smaller diameter portion; a multipole magnetic encoder ring having alternating north and south poles around its circumference to provide a magnetic signal, said encoder ring being housed in said outer ring; prevention means for preventing said rolling elements from interfering with proper operation of said magnetic encoder ring; an encoder retainer ring press fitted onto said rotatable shaft, said retainer ring having multiple crossbars and connecting means for connecting said magnetic encoder ring to said encoder retainer ring; a sensor for detecting magnetic signals from said magnetic encoder ring; and attachment means for removably attaching said sensor to said outer ring in alignment with said magnetic encoder ring.
 2. The bearing assembly according to claim 1, wherein said bearing assembly further comprises a seal assembly for sealing said outer ring to protect said bearing, said encoder ring, and said retainer ring.
 3. The bearing assembly according to claim 1, wherein said connecting means for connecting said magnetic encoder ring to said encoder retainer ring comprises at least one partial crossmember which extends radially outwardly, said partial crossmember engaging a groove formed in the inner surface of said magnetic encoder ring.
 4. The bearing assembly according to claim 1, wherein said prevention means for preventing said rolling elements from interfering with proper operation of said magnetic encoder ring comprises a shoulder between said two portions of said outer ring, whereby said rolling elements abut against said shoulder and are separated from said encoder ring by said shoulder.
 5. An antifriction bearing assembly for use with a rotatable shaft, said bearing assembly comprising:a bearing having multiple rolling elements housed in an outer ring having two portions, a larger diameter portion and a smaller diameter portion, the rolling elements being within one of said larger diameter and smaller diameter portions; a multipole magnetic encoder ring having alternating north and south poles around its circumference to provide a magnetic signal, said encoder ring being housed within the one of said portions of said outer ring not housing the rolling elements; prevention means for preventing said rolling elements from interfering with proper operation of said magnetic encoder ring; an encoder retainer ring press fitted on said rotatable shaft; a sensor for detecting magnetic signals from said magnetic encoder ring; attachment means for removably attaching said sensor to said outer ring in alignment with said magnetic encoder ring; and seal means for providing a barrier between the outer ring and the rotatable shaft.
 6. The bearing assembly according to claim 5, wherein the rolling elements are housed in the larger diameter portion of the outer ring.
 7. An antifriction bearing assembly for use with a rotatable shaft, said bearing assembly comprising:a cup-shaped outer ring having a substantially uniform thickness forming two portions, a larger diameter portion and a smaller diameter portion, one of said portions providing an outer raceway; multiple rolling elements within an annular space between the outer raceway and the rotatable shaft; a multipole magnetic encoder ring having alternating north and south poles around its circumference to provide a magnetic signal, said encoder ring being housed within the one of said portions of said outer ring not providing the outer raceway; prevention means for preventing said rolling elements from interfering with proper operation of said magnetic encoder ring; an encoder retainer ring press fitted on said rotatable shaft; a sensor for detecting magnetic signals from said magnetic encoder ring; attachment means for removably attaching said sensor to said outer ring in alignment with said magnetic encoder ring; and seal means for providing a barrier between the outer ring and the rotatable shaft.
 8. The bearing assembly according to claim 7, wherein the cup-shaped outer ring has a radially-inwardly directed flange at at least one of its axial ends such that the flange aids retention of an internal element of the bearing assembly.
 9. The bearing assembly according to claim 7, wherein said prevention means for preventing said rolling elements from interfering with proper operation of said magnetic encoder ring comprises a shoulder between said two portions of said outer ring, whereby said rolling elements abut against said shoulder and are separated from said encoder ring by said shoulder. 